Preheat your oven to 350 degrees F. Liberally grease an 8" or 9" loaf pan with cooking spray. Set aside.
In a large bowl, cream the butter and brown sugar together with an electric mixer, about 2 minutes, until fluffy and light. Beat in the pumpkin puree, followed by the eggs, one at a time. Add in the spices, baking powder, baking soda, salt, and flour and hand-stir the dry ingredients in, careful not to overmix. Over-mixing leads to tough bread that sinks in the middle. Mixture should still see streaks of white from the flour.
Spread the batter into the prepared pan and bake for approximately 45-55 minutes or until a toothpick inserted near the center comes out clean or with moist, not wet, crumbs. NOTE: the type of pan you use may increase your baking time. I like using foil pans, but glass pans or dark pans may result in a longer baking time.
Cool the bread in the pan for about 20 minutes. While bread cools, prepare your churro coating. Pour the butter into a shallow bowl, and in another shallow bowl, combine the churro coating: sugar, brown sugar, and cinnamon until blended.
Gently and carefully remove the bread from the pan and place in the shallow bowl of the butter. Using a pastry brush, brush the butter over the sides and top of the bread as if you were basting it. Make sure every square inch of the bread's surface is coated in butter! Using two spatulas to gently lift the bread from the butter and place in the shallow bowl of cinnamon sugar. Dredge the bread in the cinnamon sugar mixture, coating the sides and the top of the bread until fully coated. Let set and cool in the cinnamon sugar mixture before slicing and serving.